A Boulder County jury will resume deliberations Friday morning after spending nearly four hours Thursday weighing the fate of George Ruibal, who is on trial for the 2007 death of his girlfriend Dana Pechin in Longmont.

Ruibal, 58, is charged with second-degree murder, although the jury has been given the option of convicting him on lesser counts of manslaughter or criminal negligence.

As evidence and testimony wrapped up Thursday morning, attorneys made their closing arguments to the jury. Prosecutors argued the beating and strangulation of Pechin was the culmination of a violent and unstable relationship, while Ruibal's attorneys said there was no evidence Ruibal had done anything but try to care for Pechin when she came back to their apartment after being assaulted by a stranger.

Prosecutors say Ruibal badly beat Pechin in the small Longmont apartment that the couple had just rented in December 2007 and then took care of her until she succumbed to her injuries. Deputy District Attorney Tim Johnson described a roller-coaster relationship between the two that finally boiled over in December 2007.

"When she came home he was upset, he was angry and he assaulted her and continued to assault and savagely beat and kick her until she did not move again," Johnson said.

Johnson said there were inconsistencies in Ruibal's statements and that Pechin would not have been able to get back to the apartment on a cold, snowy night after being assaulted by a stranger, as Ruibal told police.

"She didn't wake up from this, she didn't come walking back from this," Johnson said.

But Ruibal's attorney, Eric Klein, said there simply was no evidence Ruibal was the one who assaulted Pechin. He pointed out that the prosecution kept bringing up the violence of the attack, but argued no neighbors heard a disturbance and the small apartment showed no signs of a fight. Ruibal also did not have offensive wounds on his hands and no signs of a struggle aside from some scratches on his face.

"The prosecution's case rests on inference, conjecture, speculation, but not evidence," Klein said. "The evidence and the lack of evidence in this case shows Mr. Ruibal is not guilty."

Klein again brought up Joel Dorn, who previously had been arrested on domestic violence incidents that the defense claimed were similar to what happened to Pechin. Dorn was contacted by police sometime the night the beating occurred in the area where Ruibal said Pechin had walked to.

"You are staring reasonable doubt in the face," Klein said as he displayed a mugshot of Dorn to the jury.

Klein also said Ruibal's behavior was not that of a guilty man. Ruibal cooperated with police from the time he was identified as a person of interest in 2007 until his arrest in 2011 following a grand jury indictment.

"He cooperated with police, assisted police, over and over and over again," Klein said. "He helped because he wants to find out what had happened."

But Deputy District Attorney Chris Estoll said for all his cooperation, Ruibal never called police when he saw Pechin injured in his apartment and never called during the investigation for updates on the case.

"Ask yourself, why didn't he call?" Estoll said. "He didn't call because he was the one that caused the injuries. He didn't call because he was concerned they knew what he had done.

"He said, 'All he had to do was change one fact. Change it from: it was me to it was someone else. All I have to do I cooperate and I can get away with it,'" Estoll said. "And for five years he did."

The jurors adjourned for the night at 4:30 p.m. They will continue deliberations Friday at 9 a.m.